I.Q. ushered in a new generation of signal processing. I.Q. was an intelligent tool which learned and automatically altered the spectrum of any audio to match that of any other audio. You could make a new guitar track exactly match the spectral characteristics of an older guitar track (or vice versa), allowing fast, perfect matching of punches or replacements with an accuracy beyond anything you thought possible.
I.Q. worked on any audio. Not only could it match vocals and other miked audio, but it could also handle microphones, guitar amps, and even guitars themselves.
I.Q. worked by learning the sonic spectrum of any instrument, take, or track, mono or stereo, then automatically constructed a complex filter which matched the spectrum of the new audio to the original.
I.Q. was the ideal solution for film dialog matching.
You could also use I.Q. to match the overall spectrum of your entire mix to that of any favored reference mix or commercial CD; automatically!
I.Q. has absolutely no sound of its own. I.Q. uses an FIR model in the frequency domain, and causes no phase shift or ringing. If you can’t fix it with I.Q., it’s too broke to fix.